Specifications

ALUMINUM-LITHIUM ALLOY 2099-T86
Low Density, High Strength Plate
DESCRIPTION
APPLICATIONS
Alcoa developed third-generation aluminum-lithium alloy
AA 2099 to have low density, high strength, high modulus,
moderate fracture toughness, and excellent fatigue crack
growth and corrosion resistance. The composition and
thermal mechanical processes for 2099 were especially
designed to overcome the deficiencies in earlier Al-Li alloys
such as poor corrosion resistance and high anisotropy.
Compared to alloys 7075 and 7050, alloy 2099 offers similar
strength and improved fatigue crack growth and corrosion
resistance with 6 to 7% lower density.
Alloy 2099 plate can replace alloys 7075, 7050, and
other high strength plate alloys in applications requiring high
strength and moderate fracture toughness. The fabrication
characteristics of 2099 plate are significantly improved over
second-generation Al-Li alloys such as AA 2090 and AA
8090. Customers have successfully fabricated both aircraft
and spacecraft components from 2099 plate.
COMMERCIAL STATUS
Alcoa 2099-T86 plate has been supplied commercially to a
customer specification since 2007 and is currently used for
internal aircraft structure. 2099-T86 plate is also covered
by industry specification AMS 4458 and material design
allowables are available in the MMPDS Handbook.
Alloy 2099 plate is available in the high strength T86 temper.
The available thickness range is 0.5 to 2.0 inches (12.7 to
50.8 mm).
CHEMICAL COMPOSITION Chemical Composition Limits • AA 2099 (Wt.%)*
Cu
Li
Zn
Mg
Mn
Zr
Ti
Fe
Si
Al
2.4 – 3.0
1.6 – 2.0
0.40 – 1.0
0.10 – 0.50
0.10 – 0.50
0.05 – 0.12
0.10 max
0.07 max
0.05 max
Remainder
*Other elements: 0.05 wt.% max (each); 0.15 wt.% max (total)
Static Properties • Al-Li 2099-T86 Plate • Minimum Values (S-Basis)
Alloy/Temper
Direction
Thickness, Inch (mm)
2099-T86
(AMS 4458)
7075-T7351
(AMS 4078)
7050-T7451
(AMS 4050)
0.500 – 2.000
(12.70 – 25.40)
1.001 – 2.000
(25.42 – 50.80)
0.250 – 2.000
(6.350 – 50.80)
L
71 (490)
69 (476)
74 (510)
LT
72 (496)
69 (476)
74 (510)
L
63 (434)
57 (393)
64 (441)
LT
62 (427)
57 (393)
64 (441)
L
6
na
10
LT
5
6
9
Tension Modulus, Msi (GPa)
11.3 (77.9)
10.3 (71.0)
10.3 (71.0)
Compression Modulus, Msi (GPa)
11.5 (79.3)
10.6 (73.0)
10.6 (73.0)
Density, lb/in , (g/cm )
0.095 (2.63)
0.101 (2.81)
0.102 (2.83)
Tensile Strength, Ftu, ksi (MPa)
Tensile Yield, Fty, ksi (MPa)
Elongation, %, 4D
3
3
CONTACT AND PROCUREMENT
For additional information on 2099-T86 plate, contact your local Alcoa Sales Account Manager.
FATIGUE AND DAMAGE TOLERANCE PROPERTIES
The fracture toughness and S-N fatigue resistance of 2099-T86 is similar to that of 7050-T7451, and better than that of 7075T7351. The fatigue crack growth resistance of 2099-T86 is superior to that of both 7050-T7451 and 7x75-T7351 alloys.
Fracture Toughness • 2099-T86
Alloy/Temper
Orientation
KIc Minimum
ksi√in (MPa√m)
KIc* Typical
ksi√in (MPa√m)
L-T
30 (33)
40 (44)
T-L
25 (27)
33 (36)
L-T
na
30 (33)*
T-L
na
27 (30)*
L-T
29 (32)
40 (44)*
T-L
25 (27)
33 (36)*
2099-T86 (1.00 – 2.00 in.)
7075-T7351 (> 1.00 in.)
7050-T7451 (1.00 – 2.00 in.)
* Source: MMPDS Handbook
S-N Fatigue
FCG Curves
1.0E-02
2099-T86
7050-T7451
40
T-L Orientataon
R=0.1, Humid Air,
Frequency=25 Hz
1.0E-03
30
20
10
da/dN (in/cycle)
Maximum Net Stress (ksi)
50
Longitudinal
Kt(net)=2.5 (Double Hole)
R=0.1, Lab Air
Frequency: 25-30 Hz
0
1.0E+04
1.0E+05
1.0E+06
1.0E-04
1.0E-05
1.0E-06
1.0E+07
Cycles to Failure
2099-T86
1.0E-07
7050-T7451
7475-T7351
1.0E-08
1
10
100
K (ksi in)
CORROSION RESISTANCE
The corrosion resistance of 2099-T86 plate is exceptional.
The exfoliation rating of 2099-T86 is typically P (pitting
only, ASTM G34 rating) in the accelerated Dry Bottom
MASTMAASIS tests (ASTM G 85 Annex 2) and after
many years of seacoast exposure. The guaranteed SCC
resistance of 2099-T86 (ASTM G47) is 50 ksi (345 MPa)
in the ST direction; the highest of any commercial aerospace
plate product.
SCC Resistance • 2099-T86
Alloy/Temper
Direction
SCC Minimum ksi
(MPa)
2099-T86
(0.75 – 2.00 in.)
LT
55 (370)
ST
50 (345)
7050-T7451
(> 1.00 in.)
ST
35 (241)
7075-T7351
(1.00 – 2.00 in.)
ST
43 (295)
ALCOA AEROSPACE AND AUTOMOTIVE PRODUCTS
P.O. BOX 8025 • BETTENDORF, IOWA 52722 • 1-800-523-9596 • www.alcoa.com
Product specifications are subject to change without notice.
©2016 Alcoa Inc.
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